Beauveria bassiana Effects on Ixodes scapularis Mortality for Standardization of Entomopathogenic Fungus as Biopesticide

Ticks are known for the spread of Lyme disease, and investigations into possible biological controls for their populations are always needed. Previously in Professor LoGiudice’s laboratory students worked on the correlation between invasive plant species and tick population density. Invasive plants expressing chemical allelopathy have the ability to inhibit the growth of other plants and fungi. These plants have shown higher densities of ticks than wild plant species). The present study is investigating the effects of these entomopathogenic fungi on ticks in a laboratory setting.  Ixodes scapularis or black-legged ticks were collected at the Kelly Adirondack Center in Schenectady, NY using drag cloths in low brush areas. Three experiments were designed to test the lethal dose (LD) of the entomopathogenic fungus. First, ticks were exposed to standard dilutions following the package instructions for minimum and maximum doses of Bontani Guard, a concentrated solution of the fungus, Beauveria bassiana. Ten ticks were exposed to each of the following: full strength (undiluted)  solution, the maximum recommended dose of 1:200 dilution, the minimum dose of 1:800 dilution and deionized water. Second, three weeks after exposure, surviving ticks were re-inoculated using the initial dosage. Third, to more finely estimate the  lethal dose of B.bassiana 20 ticks were each exposed to 1:100, 1:200, and 1:300 dilutions. Initial results of undiluted Botani Guard (LD100 = 72 hours) confirm that B. bassiana is a suitable fungus for Ixodidae population control. The maximum recommended dose yielded an initial LD50 = 9 days suggesting potential practical use. Additionally, ticks washed with ethanol appear to die at a higher rate when compared to ticks washed with deionized water. Experiments are ongoing but it hypothesized that re-inoculation will increase mortality at the maximum and minimum doses. It is also hypothesized that the third experiment will yield LD50 from 1 to 3 weeks.  This experiment provides insight into a lethal dose of entomopathogenic fungus for use in a laboratory setting to standardize laboratory data. Further studies investigating the effects of the B. bassiana on other insects, plants and animals are needed to determine what ecological effects the fungus may have.